Of course it doesn't, but one must prevail. The thing is, for the end user it's better if all of the UI/UX is consistant throughout the whole system, including 3rd party apps. And in most cases, it also helps the developer - but then again it stifles creativity because you, as a developer, are forced to obey some system manufacturer's guidelines, which can range from severely limited to downright frustrating.

In an ideal system, the user would be informed when installing an app that it may affect the system performance, look and feel, and let the user decide if the app is worth granting such access.

Changing the SD card resets the system for some reason, so we were reluctant to try it. And, as I understood, even then you wouldn't be able to add music to the media player that way - it's either Zune way or the highway.

Ditto, and that's one, amongst other things, that Nokia loses going the WP7 way. Granted, both PC Suite and the later Ovi Suite never got to the ease of use of competing suites, but they were still enough for a laymen - us, techies, are using rsync for years now. It even works on newer s40 devices. I can't see how that is bad for the user, and how a platform that doesn't provide you with such basic functionality is 'created with user in mind'